 
Summary: VOLUME 82, NUMBER 11 P H Y S I C A L R E V I E W L E T T E R S 15 MARCH 1999
Dynamic Instability of Brittle Fracture
Mokhtar AddaBedia,1
Rodrigo Arias,2
Martine Ben Amar,1
and Fernando Lund2
1
Laboratoire de Physique Statistique de l'Ecole Normale Supérieure, 24 rue Lhomond, F75231 Paris Cedex 05, France
2
Departamento de Fi´sica, Facultad de Ciencias Fi´sicas y Matemáticas, Universidad de Chile, Casilla 4873, Santiago, Chile
(Received 15 June 1998)
Using Eshelby's energymomentum tensor, it is shown that the elastic configurational force acting on
a moving crack tip does not necessarily point in the direction of crack propagation. A generalization of
Griffith's approach that takes into account this fact is proposed to describe dynamic crack propagation in
two dimensions. The model leads to a critical velocity below which motion proceeds in a pure opening
mode, while above it, it does not. The possible relevance of this instability to recent experimental
observations is discussed. [S00319007(99)087050]
PACS numbers: 62.20.Mk, 46.05.+b, 46.50.+a, 81.40.Np
When an elastic medium that contains a crack is subject
to an external load, the energy stored in the elastic field is
